Electron-phonon scattering in nonperiodic systems: The Si(111) surface

The self-energy associated with electron-phonon scattering is calculated for a realistic model of a Si(111) semi-infinite crystal. The method only requires a knowledge of local properties of the electrons and the phonons, and can be easily generalized to other types of nonperiodic systems. It is shown that deviations from bulk values are small, and localized at the three outermost Si layers. We trace most of these effects to the changes in the electronic density of states near the surface. Surface states couple weakly to the phonons.